Photographic emulsion



Patented Mar. 17, 1942 PHOTOGRAPHIC EMULSION Gustav Wilmanns, Wolfen, Kreis Bitterfeld, and Oskar Riester, Dessau; Germany, assignors, by

mesne assignments, to General Aniline & Film Corporation, New York, N. Y., a corporation of Delaware No Drawing. Application November is, 1939, Se-

rial No. 304-,l72. 1938 4 Claims.

sitized silver halide emulsion layers contain different dyestuif components fast to diffusion.

It has been found that not all dyestuffs can be, employed for the sensitization of such silver hal-' ide emulsions which on account of their sensitizing range would appear suitable, since many. of the known sensitizers which possess per se excellent sensitizing properties are greatly impaired or even entirely lose their sensitizing capacity in the presence of dyestufl components for colorforming development. In various prior U. S. ap

plications to the same assignee Ser. Nos. 145,066

filed May 27, 1937, 153,516 filed July 14, 1937, 279,910 filed June 19, 1939, and 280,352 filedJune 21, 1939, some groups of sensitizers have been proposed, the sensitizing action of which is not diminished by the presence of color formers.

It is an object of the invention to provide a novel silver halide emulsion containing a. colorforming development component and a dyestuff, the sensitizing act on of which is unimpaired by the presence of said component.

- A further object of the invention is the provision of sensitizing dyes suitable for use in colorforming development.

Further objects of the invention will become apparent from the detailed description following hereinafter.

We have found that for the sensitization of silver halide emulsions with dyestufi components for color-forming development rhodacyanine dyes which contain in the polymethine, chain a rhodanine ring and which have the general formula In Germany November 2,

members of heterocyclic rings or condensed heterocyclic ring systems which maybe substituted,

R1, R2, and R3 stand for H, alkyl, aralkyL. aryl,

X stands for an anion, for instance Cl, Br,

11 stand for 1 or 2,

are especially suitable. These sensitizing dyes may be prepared according to the process described in U. S. patent application Ser. No. 237,- 474 filed October 28, 1938. The dyes have a polymethine chain which is'interrupted by a rhodanine nucleus and which has at both ends nitrogen containing heterocyclic ring systems such as are well known in the chemistry of sensitizing dyes.

It must be especially emphasized that the sensitizing capacity or these dyes is not only maintainedin the presence of color-forming development components but is increased and in part [rendered more selective.. This entirely new propthe red-sensitive part of the material used for exposure, that is from orange-red to purple. This is highly important for the material used for .exvposure which necessitates'a sensitization of shorter wave lengths, as well as for the printing material in which the deep red region is employed.

It must further be noted that comparatively small amounts of the sensitization dye suiiice for the production of a satisfactorily intense and uni form sensitization whereby any coloring of the layers is prevented from the start, a feature of especial importance for the production of paper positives. At the same time, however, it is also possible to employ greater amounts of the sensi-, tizer withoutimpairing the excellent sensitizing properties. These dyes are furthermore characterized by good fastness and absence of fogging. Of the dyes which come within the general formula above given' those are also useful within the ambit of the invention the absolute sensitizing range of which is not excessive, but is sufiicient for the production of a desired intensity,- which is in conformity with the intensity of the other layers.

The following dyes may be named as examples:

| Example 1 A violet-blue dyestuff of the following constitution:

as, cm

=OH-CH=C a (1: '-cn=c N \N (BE: 0 N A:

& I I I M. Absorption maximum in methanol 585 sensitizing mP-xim'lm 615 sensitizing range.. 540 to 640 Example 2 A blue violet of the following constitution:

cm cm c=cn-cn=c 1- 0-0 H=C I A I Absorption maximum'in methanol 595 sensitizing maximum 635 sensitizing range 550 to 670 Example 3 A blue dyestufi of the following constitution:

(L H N ocmj I 01H:

, Absorption maximum in methanol. 605 sensitizing maximum 640 sensitizing range 555 to 675 Example 4 A blue dyestufl of the following constitution:

s s H10 5 \C=CHCH==C/ \C' CH-C/ m0 & Br-

& N N ,H sHa MI Absorption maximum in methanol. 605 sensitizing maximum 635 sensitizing range 545 to 675 Example 5 An ice-blue dyestufl of the following constitu tion:

Absorption maximum in methanol. 625 1m: and

tution.

JJiHl Absorption maximum in methanoL- 630 my. and

- weaker at A 685 mp sensitizing maximum 660 mp sensitizing range 595 to 670 Example 8- A violet dyestufi of the following constitution:

c cE-c g C-CH=C/ I 0130804 g i/ H: $13 JJIHI M" Absorption maximum in methanol 595 sensitizing maximum 620 sensitizing range 540 to 660 Example 9 A blue-green cLvestufi of the following constitution:

s s s mo c=cnon=cn-cn=z H co= a J: \N/ I I i l 43: 5 431K v M Absorption maximum in methanol; 670 sensitizing ma m "(15 sensitizing range 640 to 740 Example 10 A green dyestui! oithe following constitution:

/ 4 C I OH- 1. 4 2K; Q

47am 4am Mu Absorption maximum in methonol 700' sensitizing maximum I25 i Example. A green-blue dyestui! oi the constitution:

(LE1 I aHr Absorption maximum in methanol.-----..-- 675 sensitizing maximum. 710

sensitizing rang e 660 to 740 Example 12 An ice-blue dyestui! oi the following constitution: v

Absorption maximum 650 sensitizing msximum..----.. 895 sensitizing range 625 to 725 Example 13 A blue dyestuii' o! the following constitution:

- A blue-green dyestufl of the following will. tution:

- ble in aqueous liquids.

Dyestuii. components having long chain aliphaticradicals and suliogi'oups. for instance 1 N-stearoylamino- 4 N -(-l'-hydroxy 2- naphthoyl 4 sulfonic acid-sodium) phenylene-diamine (see U'. 8. patent application Ser. No. 94,340 filed August 5, 1936) and dyestui! and components with substantive; groups (see U. s. patent application Ser. No. 72,718 filed April 4, 1936) for instance a-hydroxy-naphthoic acid benzidide may be named as examples.

The dyestuii' components are added to the emulsion in an amount of about 10 grams per kilo.

We claim: 1. A silver halide emulsion containing a dyestui! component for color-forming development of the a-naphthol-series said dyestufl' component containing a aroup having a chemical constitution which hinders difl'usion of the dyestufl' component and a sensitizing dye. of the following general formula:

wherein 10 Y and Zare members of the group consisting of 15 Y and Z being members of heterocyclic rings or condensed heterocyclic ring systems which may be substituted, R1, R2, and R: stand for a member of the group r consisting of H, alkyl, aralkyl, aryl,

20 X stands for an anion, for instance Cl, Br, 1,

$04K, C104, SO4CH$r SQ4C2H5, and n stands for a whole number smaller than 3.

2. A silver halide emulsion as defined in claim 1, wherein said sensitizing dye has the following 2 constitution v 3. A silver halide emulsion asdefined in claim 1, wherein said sensitizing dye has the following constitution 4. A silver halide emulsion as defined in claim' 1, wherein said sensitizing dye has the following constitution GUSTAV WILMANNS.

OSKAR RIESTER. 

